XML 120 R103.htm IDEA: XBRL DOCUMENT
v3.19.1

Derivatives (Concentration Risk) (Details) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017
Concentration Risk [Line Items] |  |
Concentration Risk | $ 1,382 | $ 1,394
Accounts Receivable [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 88.00% | 81.00%
Concentration Risk | $ 1,215 | $ 1,141
Accounts Receivable [Member] | A- Rating [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 4.00% | 4.00%
Concentration Risk | $ 49 | $ 55
Accounts Receivable [Member] | BBB- to BBB+ Rating [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 5.00% | 4.00%
Concentration Risk | $ 70 | $ 61
Accounts Receivable [Member] | Not Rated [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 8.00% | 7.00%
Concentration Risk | $ 108 | $ 96
Accounts Receivable [Member] | CCC- to CCC+ [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 0.00% | 0.00%
Concentration Risk | $ 8 | $ 0
Accounts Receivable, Residential [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 28.00% | 23.00%
Concentration Risk | $ 384 | $ 326
Accounts Receivable, Commercial [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 13.00% | 11.00%
Concentration Risk | $ 182 | $ 161
Accounts Receivable, Industrial [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 4.00% | 3.00%
Concentration Risk | $ 57 | $ 46
Accounts Receivable, Other [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 6.00% | 7.00%
Concentration Risk | $ 84 | $ 96
Regulated utilities [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 51.00% | 44.00%
Concentration Risk | $ 707 | $ 629
Trading group [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 17.00% | 15.00%
Concentration Risk | $ 235 | $ 212
Other Accounts Receivable [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 20.00% | 22.00%
Concentration Risk | $ 273 | $ 300
Derivative [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 12.00% | 19.00%
Concentration Risk | $ 167 | $ 253
Derivative [Member] | A- Rating [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 9.00% | 15.00%
Concentration Risk | $ 130 | $ 207
Derivative [Member] | BBB- to BBB+ Rating [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 1.00% | 1.00%
Concentration Risk | $ 9 | $ 10
Derivative [Member] | Not Rated [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 2.00% | 3.00%
Concentration Risk | $ 28 | $ 36
Assets, Total [Member] | Credit Concentration Risk [Member] |  |
Concentration Risk [Line Items] |  |
Concentration Risk, Percentage | 100.00% | 100.00%

X
- Definition Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611 + Details
Name: | us-gaap_ConcentrationRiskCreditRiskFinancialInstrumentMaximumExposure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ConcentrationRiskLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_AccountsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ema_CreditRatingAxis=ema_AMinusRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ema_CreditRatingAxis=ema_BbbMinusToBbbPlusRatingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ema_CreditRatingAxis=ema_NotRatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ema_CreditRatingAxis=ema_CccToCccMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_AccountsReceivableResidentialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_AccountsReceivableCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_AccountsReceivableIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_AccountsReceivableOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_RegulatedUtilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_TradingGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=ema_OtherAccountsReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_DerivativeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_AssetsTotalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CreditConcentrationRiskMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |